Even with all that work don't you think this thing should be added since privacy is involved here? Or does it comes with other disadvantages? More cost? Please enlightened me if you can. I really don't know / can't understand why this isn't suppprted by many.
There's pull requests concerning Silent Payments for both Electrum [1] and Bitcoin Core [2] so it's presumably mostly a question of implementation complexity and prioritization. Put differently, it looks like there's work being done, but it simply takes time to integrate.
[1]
https://github.com/spesmilo/electrum/issues/9728[2]
https://github.com/bitcoin/bitcoin/pull/28122